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  • Author or Editor: Tulay Bakirel x
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The present study evaluated the effects of doxorubicin (DOX) and deracoxib (DER), as single agents and in combination treatments, on antioxidant parameters in the canine mammary carcinoma cell line CMT-U27. The cells were exposed to DOX and DER for 24, 48 and 72 h. The viability and malondialdehyde (MDA), nitric oxide (NO), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSHPx) and total glutathione (GSH) activities of CMT-U27 cells were determined. The half inhibition concentration (IC50) of DOX was found to be ∼0.9 μM in the 72-h period. IC50 and 1/10 IC50 concentrations of DOX were combined with all concentrations of DER (50–1000 μM) in the combination experiments. The results showed increased oxidative status associated with significant decreases of CAT and GSH levels in CMT-U27 cells exposed to 10-μM and higher concentrations of DOX compared to control cells. In contrast, there were no significant changes in the groups tested with any of the concentrations of DER (50–1000 μM). In combination treatments, DER attenuated DOX-induced oxidative damage by modulating the enzymatic and non-enzymatic components in CMT-U27 cells. We suggest that the combination of DOX and DER can be beneficial in the treatment of cancer cells by increasing cellular responses to oxidative stress. In conclusion, the use of COX inhibitor in conjunction with a chemotherapeutic agent may provide a basis for new concepts of cancer treatment through systematic modulation of the antioxidant defence systems in mammary cancers of animals.

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Authors: Tulay Bakirel, Fulya Ustun Alkan, Oya Ustuner, Suzan Çinar, Ceren Anlas and Ataman Bilge Sari

Currently, there is a growing interest in combining anticancer drugs with the aim to improve outcome in patients suffering from tumours and reduce the long-term toxicity associated with the current standard of treatment. In this study, we evaluated the possible role of deracoxib against the toxicity of doxorubicin on normal canine mammary epithelial cells. The effect of deracoxib and doxorubicin combination on cell viability was determined by MTT assay. Apoptosis was characterised by flow cytometry. Cell nitrite concentrations were measured with the Griess reaction. Deracoxib (50 and 100 μM) treatment decreased the cytotoxic action of doxorubicin at 0.9 μM in the cells, from 33.63% to 13.4% and 25.82%, respectively. Our results also showed that the reverse effect of deracoxib on doxorubicin-induced cytotoxic activity in the cells was associated with a marked (3.04- to 3.57-fold) decrease in apoptosis. In additional studies identifying the mechanism of the observed effect, deracoxib exhibited an activity to prevent doxorubicin-mediated overproduction of nitric oxide in the cells. Our in vitro study results indicate that deracoxib (50 and 100 μM) can be beneficial in protecting normal cells from the toxic effect of doxorubicin in conjunction with apoptosis by the modulation of nitric oxide production.

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